Isomeric structural characterization of polyhedral oligomeric silsesquioxanes (POSS) with styryl and epoxy phenyl capping agents

Ion mobility and molecular modeling methods were used to examine the gas-phase structures of sodiated POSS capped with styryl and epoxy phenyl substituents (Na(+)Sty(x)Ep(8-x)T(8)). Results were obtained for x = 5-7 and indicated that three distinct isomers with different collision cross-sections were present for each value of x. Theoretical modeling also yielded three different families of structures for each POSS system, and their calculated cross-sections agreed very well with experimental values (<1% difference). For Na(+)Sty(7)EpT(8,), the three families differ in the number of "paired" Sty groups. For Na(+)Sty(6)Ep(2)T(8) and Na(+)Sty(5)Ep(3)T(8), the three isomers correspond to the three different ways the Ep groups can be positioned on the POSS cage.